U.S. patent application number 11/417006 was filed with the patent office on 2007-07-26 for physiological measurement communications adapter.
Invention is credited to Ammar Al-Ali.
Application Number | 20070173701 11/417006 |
Document ID | / |
Family ID | 28045707 |
Filed Date | 2007-07-26 |
United States Patent
Application |
20070173701 |
Kind Code |
A1 |
Al-Ali; Ammar |
July 26, 2007 |
Physiological measurement communications adapter
Abstract
A sensor signal is input at a patient location and a
physiological waveform responsive to the sensor signal is
generated. The physiological waveform is wirelessly communicated
from the patient location to a monitor location. The physiological
waveform is adapted to a particular patient monitor at the monitor
location. The adapted physiological waveform is output to a sensor
port of the patient monitor. Accordingly, the patient monitor
derives physiological measurements from the adapted physiological
waveform that are generally equivalent to measurements derivable
from the physiological waveform by a monitor compatible with the
sensor signal.
Inventors: |
Al-Ali; Ammar; (Tustin,
CA) |
Correspondence
Address: |
LAW OFFICE OF GLENN R. SMITH
28626 BROOKHILL ROAD
TRABUCO CANYON
CA
92679-1163
US
|
Family ID: |
28045707 |
Appl. No.: |
11/417006 |
Filed: |
May 3, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11048330 |
Feb 1, 2005 |
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11417006 |
May 3, 2006 |
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10377933 |
Feb 28, 2003 |
6850788 |
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11048330 |
Feb 1, 2005 |
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60367428 |
Mar 25, 2002 |
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Current U.S.
Class: |
600/300 ;
128/903; 600/323 |
Current CPC
Class: |
Y10S 128/903 20130101;
A61B 5/021 20130101; A61B 5/7271 20130101; A61B 5/6824 20130101;
A61B 5/0004 20130101; A61B 5/7425 20130101; A61B 5/02427 20130101;
A61B 5/1455 20130101; A61B 5/14552 20130101; A61B 5/0015 20130101;
A61B 5/6838 20130101; A61B 5/72 20130101; A61B 5/7228 20130101;
A61B 2562/227 20130101; A61B 5/7445 20130101; A61B 5/0026 20130101;
A61B 5/332 20210101; A61B 5/02438 20130101; A61B 2562/222 20130101;
A61B 5/0205 20130101; A61B 5/002 20130101; A61B 5/30 20210101; H04W
4/70 20180201; A61B 2560/0214 20130101; A61B 5/318 20210101; A61B
5/6826 20130101; A61B 5/7475 20130101; G08B 21/0453 20130101; A61B
5/0024 20130101; A61B 5/742 20130101; A61B 5/6831 20130101 |
Class at
Publication: |
600/300 ;
128/903; 600/323 |
International
Class: |
A61B 5/00 20060101
A61B005/00 |
Claims
1. A communications adapter configured to wirelessly communicate a
physiological waveform from a patient site to a remote site and to
adapt the physiological waveform to a particular patient monitor at
the remote site, the communications adapter comprising: a first
processor configured to generate a physiological waveform
responsive to a sensor signal received from a noninvasive sensor
attached to a tissue portion of a patient; a communications link
configured to wirelessly transmit the physiological waveform from a
first site proximate the patient and to receive the physiological
waveform at a second site; and a second processor that adapts the
physiological waveform to a particular patient monitor at the
second site so that the particular patient monitor derives
physiological measurements from the adapted physiological waveform
that are generally equivalent to measurements derivable from the
physiological waveform by a monitor compatible with the noninvasive
sensor.
2. The communications adapter according to claim 1 further
comprising: a physiological measurement made at the first site and
transmitted to the second site; and a characterization
corresponding to the particular patient monitor that relates
predetermined physiological waveform aspects to predetermined
physiological measurement values, wherein the physiological
waveform is adapted to the particular patient monitor according to
the physiological measurement and the characterization.
3. The communications adapter according to claim 2 further
comprising: a monitor module housing at least a portion of the
communications link and the second processor, the monitor module
configured to communicate with a sensor port of the monitor; and a
memory associated with the monitor module configured to store data
corresponding to the characterization.
4. The communications adapter according to claim 2 further
comprising: a monitor module housing at least a portion of the
communications link and the second processor; a cable configured to
provide wired communications between the monitor module and a
sensor port of the patient monitor; and a memory associated with
the cable and configured to store data corresponding to the
characterization.
5. The communications adapter according to claim 2 wherein a
physiological measurement comprising at least one of oxygen
saturation, blood pressure, EKG, respiration rate, body temperature
and blood glucose can be derived from the adapted physiological
waveform.
6. The communications adapter according to claim 2 wherein a
plurality of physiological measurements comprising at least two of
oxygen saturation, blood pressure, EKG, respiration rate, body
temperature and blood glucose can be derived from the adapted
physiological waveform.
7. The communications adapter according to claim 5 wherein the
physiological measurement is oxygen saturation and the
physiological waveform is a plethysmograph responsive to at least
one of red and IR wavelengths emitted by the noninvasive
sensor.
8. A physiological measurement method comprising: inputting a
sensor signal at a patient location; generating a physiological
waveform responsive to the sensor signal; reducing the sample rate
of the physiological waveform; wirelessly communicating the reduced
sample rate physiological waveform from the patient location to a
monitor location; adapting the reduced sample rate physiological
waveform to a particular patient monitor at the monitor location;
and outputting the adapted physiological waveform to a sensor port
of the patient monitor so that the patient monitor derives
physiological measurements from the adapted physiological waveform
that are generally equivalent to measurements derivable from the
physiological waveform by a monitor compatible with the sensor
signal.
9. The physiological measurement method according to claim 8
further comprising: measuring a physiological parameter responsive
to the sensor signal; and wirelessly communicating the
physiological parameter from the patient location to the monitor
location.
10. The physiological measurement method according to claim 9
further comprising characterizing the particular patient monitor
according to the physiological parameter and the adapted
physiological waveform.
11. The physiological measurement method according to claim 10
wherein adapting comprises modifying the physiological waveform
according to the physiological parameter and the
characterization.
12. The physiological measurement method according to claim 11
wherein generating comprises deriving a plethysmograph responsive
to at least one of an IR wavelength portion and a red wavelength
portion of the sensor signal.
13. The physiological measurement method according to claim 12
wherein characterizing comprises storing a plurality of red/IR
values and corresponding plurality of oxygen saturation values in a
memory according to the particular patient monitor.
14. The physiological measurement method according to claim 13
wherein adapting comprises relatively scaling an IR plethysmograph
corresponding to the IR wavelength sensor signal portion and a red
plethysmograph corresponding to the red wavelength sensor signal
portion.
15. The physiological measurement method according to claim 14
wherein outputting comprises communicating the scaled red and IR
plethysmographs to the sensor port of the patient monitor.
16. A communications adapter comprising: a sensor interface means
for inputting a sensor signal from a noninvasive sensor attached to
a patient tissue site; a first processor means for generating a
physiological waveform responsive to the sensor signal; a wireless
communications means for communicating the physiological waveform
from a patient location to a monitor location; a second processor
means for adapting the physiological waveform to a particular
monitor at the monitor location; and a monitor interface means for
outputting the adapted physiological waveform to a sensor port of
the monitor.
17. The communications adapter according to claim 16 further
comprising: a characterization means for relating the adapted
physiological waveform and physiological parameter measurements
according to the particular monitor.
18. The communications adapter according to claim 17 further
comprising a third processor means for reducing the sampling rate
of the physiological waveform prior to the wireless communications
of the physiological waveform to the monitor location.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority benefit under 35
U.S.C. .sctn. 120 to, and is a continuation of, U.S. patent
application Ser. No. 11/048,330, filed Feb. 1, 2005 entitled
"Physiological Measurement Communications Adapter," which is a
continuation of U.S. Pat. No. 6,850,788, entitled "Physiological
Measurement Communications Adapter," which claims priority benefit
under 35 U.S.C. .sctn. 119(e) from U.S. Provisional Application No.
60/367,428, filed Mar. 25, 2002, entitled "Physiological
Measurement Communications Adapter." The present application also
incorporates the foregoing utility disclosures herein by
reference.
BACKGROUND OF THE INVENTION
[0002] Patient vital sign monitoring may include measurements of
blood oxygen, blood pressure, respiratory gas, and EKG among other
parameters. Each of these physiological parameters typically
require a sensor in contact with a patient and a cable connecting
the sensor to a monitoring device. For example, FIGS. 1-2
illustrate a conventional pulse oximetry system 100 used for the
measurement of blood oxygen. As shown in FIG. 1, a pulse oximetry
system has a sensor 110, a patient cable 140 and a monitor 160. The
sensor 110 is typically attached to a finger 10 as shown. The
sensor 110 has a plug 118 that inserts into a patient cable socket
142. The monitor 160 has a socket 162 that accepts a patient cable
plug 144. The patient cable 140 transmits an LED drive signal 252
(FIG. 2) from the monitor 160 to the sensor 110 and a resulting
detector signal 254 (FIG. 2) from the sensor 110 to the monitor
160. The monitor 160 processes the detector signal 254 (FIG. 2) to
provide, typically, a numerical readout of the patient's oxygen
saturation, a numerical readout of pulse rate, and an audible
indicator or "beep" that occurs in response to each arterial
pulse.
[0003] As shown in FIG. 2, the sensor 110 has both red and infrared
LED emitters 212 and a photodiode detector 214. The monitor 160 has
a sensor interface 271, a signal processor 273, a controller 275,
output drivers 276, a display and audible indicator 278, and a
keypad 279. The monitor 160 determines oxygen saturation by
computing the differential absorption by arterial blood of the two
wavelengths emitted by the sensor emitters 212, as is well-known in
the art. The sensor interface 271 provides LED drive current 252
which alternately activates the red and IR LED emitters 212. The
photodiode detector 214 generates a signal 254 corresponding to the
red and infrared light energy attenuated from transmission through
the patient finger 10 (FIG. 1). The sensor interface 271 also has
input circuitry for amplification, filtering and digitization of
the detector signal 254. The signal processor 273 calculates a
ratio of detected red and infrared intensities, and an arterial
oxygen saturation value is empirically determined based on that
ratio. The controller 275 provides hardware and software interfaces
for managing the display and audible indicator 278 and keypad 279.
The display and audible indicator 278 shows the computed oxygen
status, as described above, and provides the pulse beep as well as
alarms indicating oxygen desaturation events. The keypad 279
provides a user interface for setting alarm thresholds, alarm
enablement, and display options, to name a few.
SUMMARY OF THE INVENTION
[0004] Conventional physiological measurement systems are limited
by the patient cable connection between sensor and monitor. A
patient must be located in the immediate vicinity of the monitor.
Also, patient relocation requires either disconnection of
monitoring equipment and a corresponding loss of measurements or an
awkward simultaneous movement of patient equipment and cables.
Various devices have been proposed or implemented to provide
wireless communication links between sensors and monitors, freeing
patients from the patient cable tether. These devices, however, are
incapable of working with the large installed base of existing
monitors and sensors, requiring caregivers and medical institutions
to suffer expensive wireless upgrades. It is desirable, therefore,
to provide a communications adapter that is plug-compatible both
with existing sensors and monitors and that implements a wireless
link replacement for the patient cable.
[0005] One aspect of a physiological measurement communications
adapter is a sensor signal input at a patient location. A
physiological waveform responsive to the sensor signal is
generated. The physiological waveform is wirelessly communicated
from the patient location to a monitor location. The physiological
waveform is adapted to a particular patient monitor at the monitor
location. The adapted physiological waveform is output to a sensor
port of the patient monitor. Accordingly, the patient monitor
derives physiological measurements from the adapted physiological
waveform that are generally equivalent to measurements derivable
from the physiological waveform by a monitor compatible with the
sensor signal.
[0006] Another aspect of a physiological measurement communications
adapter is an input sensor signal at a patient location. A
physiological waveform responsive to the sensor signal is
generated. The sample rate of the physiological waveform is
reduced, and the reduced sample rate physiological waveform is
wirelessly transmitted from the patient location to a monitor
location. The reduced sample rate physiological waveform is adapted
to a particular patient monitor at the monitor location. The
adapted physiological waveform is output to a sensor port of the
patient monitor so that the patient monitor derives physiological
measurements from the adapted physiological waveform that are
generally equivalent to measurements derivable from the
physiological waveform by a monitor compatible with the sensor
signal.
[0007] A further aspect of a physiological measurement
communications adapter is a sensor interface means for inputting a
sensor signal from a noninvasive sensor attached to a patient
tissue site and a first processor means for generating a
physiological waveform responsive to the sensor signal. The
communications adapter also has a wireless communications means for
communicating the physiological waveform from a patient location to
a monitor location and a second processor means for adapting the
physiological waveform to a particular monitor at the monitor
location. In addition, the communications adapter has a monitor
interface means for outputting the adapted physiological waveform
to a sensor port of the monitor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is an illustration of a prior art pulse oximetry
system;
[0009] FIG. 2 is a functional block diagram of a prior art pulse
oximetry system;
[0010] FIG. 3 is an illustration of a physiological measurement
communications adapter;
[0011] FIGS. 4A-B are illustrations of communications adapter
sensor modules;
[0012] FIGS. 5A-C are illustrations of communications adapter
monitor modules;
[0013] FIG. 6 is a functional block diagram of a communications
adapter sensor module;
[0014] FIG. 7 is a functional block diagram of a communications
adapter monitor module;
[0015] FIG. 8 is a functional block diagram of a sensor module
configured to transmit measured pulse oximeter parameters;
[0016] FIG. 9 is a functional block diagram of a monitor module
configured to received measured pulse oximeter parameters;
[0017] FIG. 10 is a functional block diagram of a sensor module
configured to transmit a plethysmograph;
[0018] FIG. 11 is a functional block diagram of a monitor module
configured to receive a plethysmograph;
[0019] FIG. 12 is a functional block diagram of a waveform
modulator;
[0020] FIG. 13 is a functional block diagram of a sensor module
configured for multiple sensors; and
[0021] FIG. 14 is a functional block diagram of a monitor module
configured for multiple sensors.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Overview
[0022] FIG. 3 illustrates one embodiment of a communications
adapter. FIGS. 4-5 illustrate physical configurations for a
communications adapter. In particular, FIGS. 4A-B illustrate sensor
module configurations and FIGS. 5A-C illustrate monitor module
configurations. FIGS. 6-14 illustrate communications adapter
functions. In particular, FIGS. 6-7 illustrate general functions
for a sensor module and a monitor module, respectively. FIGS. 8-9
functionally illustrate a communications adapter where derived
pulse oximetry parameters, such as saturation and pulse rate are
transmitted between a sensor module and a monitor module. Also,
FIGS. 10-12 functionally illustrate a communications adapter where
a plethysmograph is transmitted between a sensor module and a
monitor module. FIGS. 13-14 functionally illustrate a
multiple-parameter communications adapter.
[0023] FIG. 3 illustrates a communications adapter 300 having a
sensor module 400 and a monitor module 500. The communications
adapter 300 communicates patient data derived from a sensor 310
between the sensor module 400, which is located proximate a patient
20 and the monitor module 500, which is located proximate a monitor
360. A wireless link 340 is provided between the sensor module 400
and the monitor module 500, replacing the conventional patient
cable, such as a pulse oximetry patient cable 140 (FIG. 1).
Advantageously, the sensor module 400 is plug-compatible with a
conventional sensor 310. In particular, the sensor connector 318
connects to the sensor module 400 in a similar manner as to a
patient cable. Further, the sensor module 400 outputs a drive
signal to the sensor 310 and inputs a sensor signal from the sensor
310 in an equivalent manner as a conventional monitor 360. The
sensor module 400 may be battery powered or externally powered.
External power may be for recharging internal batteries or for
powering the sensor module during operation or both.
[0024] As shown in FIG. 3, the monitor module 500 is advantageously
plug-compatible with a conventional monitor 360. In particular, the
monitors sensor port 362 connects to the monitor module 500 in a
similar manner as to a patient cable, such as a pulse oximetry
patient cable 140 (FIG. 1). Further, the monitor module 500 inputs
a drive signal from the monitor 360 and outputs a corresponding
sensor signal to the monitor 360 in an equivalent manner as a
conventional sensor 310. As such, the combination sensor module 400
and monitor module 500 provide a plug-compatible wireless
replacement for a patient cable, adapting an existing wired
physiological measurement system into a wireless physiological
measurement system. The monitor module 500 may be battery powered,
powered from the monitor, such as by tapping current from a
monitor's LED drive, or externally powered from an independent AC
or DC power source.
[0025] Although a communications adapter 300 is described herein
with respect to a pulse oximetry sensor and monitor, one of
ordinary skill in the art will recognize that a communications
adapter may provide a plug-compatible wireless replace for a
patient cable that connects any physiological sensor and
corresponding monitor. For example, a communications adapter 300
may be applied to a biopotential sensor, a non-invasive blood
pressure (NIBP) sensor, a respiratory rate sensor, a glucose sensor
and the corresponding monitors, to name a few.
Sensor Module Physical Configurations
[0026] FIGS. 4A-B illustrate physical embodiments of a sensor
module 400. FIG. 4A illustrates a wrist-mounted module 410 having a
wrist strap 411, a case 412 and an auxiliary cable 420. The case
412 contains the sensor module electronics, which are functionally
described with respect to FIG. 6, below. The case 412 is mounted to
the wrist strap 411, which attaches the wrist-mounted module 410 to
a patient 20. The auxiliary cable 420 mates to a sensor connector
318 and a module connector 414, providing a wired link between a
conventional sensor 310 and the wrist-mounted module 410.
Alternatively, the auxiliary cable 420 is directly wired to the
sensor module 400. The wrist-mounted module 410 may have a display
415 that shows sensor measurements, module status and other visual
indicators, such as monitor status. The wrist-mounted module 410
may also have keys (not shown) or other input mechanisms to control
its operational mode and characteristics. In an alternative
embodiment, the sensor 310 may have a tail (not shown) that
connects directly to the wrist-mounted module 410, eliminating the
auxiliary cable 420.
[0027] FIG. 4B illustrates a clip-on module 460 having a clip 461,
a case 462 and an auxiliary cable 470. The clip 461 attaches the
clip-on module 460 to patient clothing or objects near a patient
20, such as a bed frame. The auxiliary cable 470 mates to the
sensor connector 318 and functions as for the auxiliary cable 420
(FIG. 4A) of the wrist-mounted module 410 (FIG. 4A), described
above. The clip-on module 460 may have a display 463 and keys 464
as for the wrist-mounted module 410 (FIG. 4A). Either the
wrist-mounted module 410 or the clip-on module 460 may have other
input or output ports (not shown) that download software, configure
the module, or provide a wired connection to other measurement
instruments or computing devices, to name a few examples.
Monitor Module Physical Configurations
[0028] FIGS. 5A-C illustrate physical embodiments of a monitor
module 500. FIG. 5A illustrates a direct-connect module 510 having
a case 512 and an integrated monitor connector 514. The case 512
contains the monitor module electronics, which are functionally
described with respect to FIG. 7, below. The monitor connector 514
mimics that of the monitor end of a patient cable, such as a pulse
oximetry patient cable 140 (FIG. 1), and electrically and
mechanically connects the monitor module 510 to the monitor 360 via
the monitor's sensor port 362.
[0029] FIG. 5B illustrates a cable-connect module 540 having a case
542 and an auxiliary cable 550. The case 542 functions as for the
direct-connect module 510 (FIG. 5A), described above. Instead of
directly plugging into the monitor 360, the cable-connect module
540 utilizes the auxiliary cable 550, which mimics the monitor end
of a patient cable, such as a pulse oximetry patient cable 140
(FIG. 1), and electrically connects the cable-connect module 540 to
the monitor sensor port 362.
[0030] FIG. 5C illustrates a plug-in module 570 having a plug-in
case 572 and an auxiliary cable 580. The plug-in case 572 is
mechanically compatible with the plug-in chassis of a
multiparameter monitor 370 and may or may not electrically connect
to the chassis backplane. The auxiliary cable 580 mimics a patient
cable and electrically connects the plug-in module 570 to the
sensor port 372 of another plug-in device. A direct-connect module
510 (FIG. 5A) or a cable-connect module 540 (FIG. 5B) may also be
used with a multiparameter monitor 370.
[0031] In a multiparameter embodiment, such as described with
respect to FIGS. 13-14, below, a monitor module 500 may connect to
multiple plug-in devices of a multiparameter monitor 370. For
example, a cable-connect module 540 (FIG. 5B) may have multiple
auxiliary cables 550 (FIG. 5B) that connect to multiple plug-in
devices installed within a multiparameter monitor chassis.
Similarly, a plug-in module 570 may have one or more auxiliary
cables 580 with multiple connectors for attaching to the sensor
ports 372 of multiple plug-in devices.
Communications Adapter Functions
[0032] FIGS. 6-7 illustrate functional embodiments of a
communications adapter. FIG. 6 illustrates a sensor module 400
having a sensor interface 610, a signal processor 630, an encoder
640, a transmitter 650 and a transmitting antenna 670. A
physiological sensor 310 provides an input sensor signal 612 at the
sensor connector 318. Depending on the sensor 310, the sensor
module 400 may provide one or more drive signals 618 to the sensor
310. The sensor interface 610 inputs the sensor signal 612 and
outputs a conditioned signal 614. The conditioned signal 614 may be
coupled to the transmitter 650 or further processed by a signal
processor 630. If the sensor module configuration utilizes a signal
processor 630, it derives a parameter signal 632 responsive to the
sensor signal 612, which is then coupled to the transmitter 650.
Regardless, the transmitter 650 inputs a baseband signal 642 that
is responsive to the sensor signal 612. The transmitter 650
modulates the baseband signal 642 with a carrier to generate a
transmit signal 654. The transmit signal 654 may be derived by
various amplitude, frequency or phase modulation schemes, as is
well known in the art. The transmit signal 654 is coupled to the
transmit antenna 670, which provides wireless communications to a
corresponding receive antenna 770 (FIG. 7), as described below.
[0033] As shown in FIG. 6, the sensor interface 610 conditions and
digitizes the sensor signal 612 to generate the conditioned signal
614. Sensor signal conditioning may be performed in the analog
domain or digital domain or both and may include amplification and
filtering in the analog domain and filtering, buffering and data
rate modification in the digital domain, to name a few. The
resulting conditioned signal 614 is responsive to the sensor signal
612 and may be used to calculate or derive a parameter signal
632.
[0034] Further shown in FIG. 6, the signal processor 630 performs
signal processing on the conditioned signal 614 to generate the
parameter signal 632. The signal processing may include buffering,
digital filtering, smoothing, averaging, adaptive filtering and
frequency transforms to name a few. The resulting parameter signal
632 may be a measurement calculated or derived from the conditioned
signal, such as oxygen saturation, pulse rate, blood glucose, blood
pressure and EKG to name a few. Also, the parameter signal 632 may
be an intermediate result from which the above-stated measurements
may be calculated or derived.
[0035] As described above, the sensor interface 610 performs mixed
analog and digital pre-processing of an analog sensor signal and
provides a digital output signal to the signal processor 630. The
signal processor 630 then performs digital post-processing of the
front-end processor output. In alternative embodiments, the input
sensor signal 612 and the output conditioned signal 614 may be
either analog or digital, the front-end processing may be purely
analog or purely digital, and the back-end processing may be purely
analog or mixed analog or digital.
[0036] In addition, FIG. 6 shows an encoder 640, which translates a
digital word or serial bit stream, for example, into the baseband
signal 642, as is well-known in the art. The baseband signal 642
comprises the symbol stream that drives the transmit signal 654
modulation, and may be a single signal or multiple related signal
components, such as in-phase and quadrature signals. The encoder
640 may include data compression and redundancy, also well-known in
the art.
[0037] FIG. 7 illustrates a monitor module 500 having a receive
antenna 770, a receiver 710, a decoder 720, a waveform processor
730 and a monitor interface 750. A receive signal 712 is coupled
from the receive antenna 770, which provides wireless
communications to a corresponding transmit antenna 670 (FIG. 6), as
described above. The receiver 710 inputs the receive signal 712,
which corresponds to the transmit signal 654 (FIG. 6). The receiver
710 demodulates the receive signal to generate a baseband signal
714. The decoder 720 translates the symbols of the demodulated
baseband signal 714 into a decoded signal 724, such as a digital
word stream or bit stream. The waveform processor 730 inputs the
decoded signal 724 and generates a constructed signal 732. The
monitor interface 750 is configured to communicate the constructed
signal 732 to a sensor port 362 of a monitor 360. The monitor 360
may output a sensor drive signal 754, which the monitor interface
750 inputs to the waveform processor 730 as a monitor drive signal
734. The waveform processor 730 may utilize the monitor drive
signal 734 to generate the constructed signal 732. The monitor
interface 750 may also provide characterization information 758 to
the waveform processor 730, relating to the monitor 360, the sensor
310 or both, that the waveform processor 730 utilizes to generate
the constructed signal 732.
[0038] The constructed signal 732 is adapted to the monitor 360 so
that measurements derived by the monitor 360 from the constructed
signal 732 are generally equivalent to measurements derivable from
the sensor signal 612 (FIG. 6). Note that the sensor 310 (FIG. 6)
may or may not be directly compatible with the monitor 360. If the
sensor 310 (FIG. 6) is compatible with the monitor 360, the
constructed signal 732 is generated so that measurements derived by
the monitor 360 from the constructed signal 732 are generally
equivalent (within clinical significance) with those derivable
directly from the sensor signal 612 (FIG. 6). If the sensor 310
(FIG. 6) is not compatible with the monitor 360, the constructed
signal 732 is generated so that measurements derived by the monitor
360 from the constructed signal 732 are generally equivalent to
those derivable directly from the sensor signal 612 (FIG. 6) using
a compatible monitor.
Wireless Pulse Oximetry
[0039] FIGS. 8-11 illustrate pulse oximeter embodiments of a
communications adapter. FIGS. 8-9 illustrate a sensor module and a
monitor module, respectively, configured to communicate measured
pulse oximeter parameters. FIGS. 10-11 illustrate a sensor module
and a monitor module, respectively, configured to communicate a
plethysmograph signal.
[0040] Parameter Transmission
[0041] FIG. 8 illustrates a pulse oximetry sensor module 800 having
a sensor interface 810, signal processor 830, encoder 840,
transmitter 850, transmitting antenna 870 and controller 890. The
sensor interface 810, signal processor 830 and controller 890
function as described with respect to FIG. 2, above. The sensor
interface 810 communicates with a standard pulse oximetry sensor
310, providing an LED drive signal 818 to the LED emitters 312 and
receiving a sensor signal 812 from the detector 314 in response.
The sensor interface 810 provides front-end processing of the
sensor signal 812, also described above, providing a plethysmograph
signal 814 to the signal processor 830. The signal processor 830
then derives a parameter signal 832 that comprises a real time
measurement of oxygen saturation and pulse rate. The parameter
signal 832 may include other parameters, such as measurements of
perfusion index and signal quality. In one embodiment, the signal
processor is an MS-5 or MS-7 board available from Masimo
Corporation, Irvine, Calif.
[0042] As shown in FIG. 8, the encoder 840, the transmitter 850 and
the transmitting antenna 870 function as described with respect to
FIG. 6, above. For example, the parameter signal 832 may be a
digital word stream that is serialized into a bit stream and
encoded into a baseband signal 842. The baseband signal 842 may be,
for example, two bit symbols that drive a quadrature phase shift
keyed (QPSK) modulator in the transmitter 850. Other encodings and
modulations are also applicable, as described above. The
transmitter 850 inputs the baseband signal 842 and generates a
transmit signal 854 that is a modulated carrier having a frequency
suitable for short-range transmission, such as within a hospital
room, doctor's office, emergency vehicle or critical care ward, to
name a few. The transmit signal 854 is coupled to the transmit
antenna 870, which provides wireless communications to a
corresponding receive antenna 970 (FIG. 9), as described below.
[0043] FIG. 9 illustrates a monitor module 900 having a receive
antenna 970, a receiver 910, a decoder 920, a waveform generator
930 and an interface cable 950. The receive antenna 970, receiver
910 and decoder 920 function as described with respect to FIG. 7,
above. In particular, the receive signal 912 is coupled from the
receive antenna 970, which provides wireless communications to a
corresponding transmit antenna 870 (FIG. 8). The receiver 910
inputs the receive signal 912, which corresponds to the transmit
signal 854 (FIG. 8). The receiver 810 demodulates the receive
signal 912 to generate a baseband signal 914. Not accounting for
transmission errors, the baseband signal 914 corresponds to the
sensor module baseband signal 842 (FIG. 8), for example a symbol
stream of two bits each. The decoder 920 assembles the baseband
signal 914 into a parameter signal 924, which, for example, may be
a sequence of digital words corresponding to oxygen saturation and
pulse rate. Again, not accounting for transmission errors, the
monitor module parameter signal 924 corresponds to the sensor
module parameter signal 832 (FIG. 8), derived by the signal
processor 830 (FIG. 8).
[0044] Also shown in FIG. 9, the waveform generator 930 is a
particular embodiment of the waveform processor 730 (FIG. 7)
described above. The waveform generator 930 generates a synthesized
waveform 932 that the pulse oximeter monitor 360 can process to
calculate SpO.sub.2 and pulse rate values or exception messages. In
the present embodiment, the waveform generator output does not
reflect a physiological waveform. In particular, the synthesized
waveform is not physiological data from the sensor module 800, but
is a waveform synthesized from predetermined stored waveform data
to cause the monitor 360 to calculate oxygen saturation and pulse
rate equivalent to or generally equivalent (within clinical
significance) to that calculated by the signal processor 830 (FIG.
8). The actual intensity signal from the patient received by the
detector 314 (FIG. 8) is not provided to the monitor 360 in the
present embodiment. Indeed, the waveform provided to the monitor
360 will usually not resemble a plethysmographic waveform or other
physiological data from the patient to whom the sensor module 800
(FIG. 8) is attached.
[0045] The synthesized waveform 932 is modulated according to the
drive signal input 934. That is, the pulse oximeter monitor 360
expects to receive a red and IR modulated intensity signal
originating from a detector, as described with respect to FIGS.
1-2, above. The waveform generator 930 generates the synthesized
waveform 932 with a predetermined shape, such as a triangular or
sawtooth waveform stored in waveform generator memory or derived by
a waveform generator algorithm. The waveform is modulated
synchronously with the drive input 934 with first and second
amplitudes that are processed in the monitor 360 as red and IR
portions of a sensor signal. The frequency and the first and second
amplitudes are adjusted so that pulse rate and oxygen saturation
measurements derived by the pulse oximeter monitor 360 are
generally equivalent to the parameter measurements derived by the
signal processor 830 (FIG. 8), as described above. One embodiment
of a waveform generator 930 is described in U.S. patent application
Ser. No. 60/117,097 entitled "Universal/Upgrading Pulse Oximeter,"
assigned to Masimo Corporation, Irvine, Calif. and incorporated by
reference herein. Although the waveform generator 930 is described
above as synthesizing a waveform that does not resemble a
physiological signal, one of ordinary skill will recognize that
another embodiment of the waveform generator 930 could incorporate,
for example, a plethysmograph simulator or other physiological
signal simulator.
[0046] Further shown in FIG. 9, the interface cable 950 functions
in a manner similar to the monitor interface 750 (FIG. 7) described
above. The interface cable 950 is configured to communicate the
synthesized waveform 932 to the monitor 360 sensor port and to
communicate the sensor drive signal 934 to the waveform generator
930. The interface cable 950 may include a ROM 960 that contains
monitor and sensor characterization data. The ROM 960 is read by
the waveform generator 930 so that the synthesized waveform 932 is
adapted to a particular monitor 360. For example, the ROM 960 may
contain calibration data of red/IR versus oxygen saturation,
waveform amplitude and waveform shape information. An interface
cable is described in U.S. patent application Ser. No. 60/117,092,
referenced above. Monitor-specific SatShare.TM. brand interface
cables are available from Masimo Corporation, Irvine, Calif. In an
alternative embodiment, such as a direct connect monitor module as
illustrated in FIG. 5A, an interface cable 950 is not used and the
ROM 960 may be incorporated within the monitor module 900
itself.
[0047] Plethysmograph Transmission
[0048] FIG. 10 illustrates another pulse oximetry sensor module
1000 having a sensor interface 1010, encoder 1040, transmitter
1050, transmitting antenna 1070 and controller 1090, which have the
corresponding functions as those described with respect to FIG. 8,
above. The encoder 1040, however, inputs a plethysmograph signal
1014 rather than oxygen saturation and pulse rate measurements 832
(FIG. 8). Thus, the sensor module 1000 according to this embodiment
encodes and transmits a plethysmograph signal 1014 to a
corresponding monitor module 1100 (FIG. 11) in contrast to derived
physiological parameters, such as oxygen saturation and pulse rate.
The plethysmograph signal 1014 is illustrated in FIG. 10 as being a
direct output from the sensor interface 1010. In another
embodiment, the sensor module 1000 incorporates a decimation
processor, not shown, after the sensor interface 1010 so as to
provide a plethysmograph signal 1014 having a reduced sample
rate.
[0049] FIG. 11 illustrates another pulse oximetry monitor module
1100 having a receive antenna 1170, a receiver 1110, a decoder 1120
and an interface cable 1150, which have the corresponding functions
as those described with respect to FIG. 9, above. This monitor
module embodiment 1100, however, has a waveform modulator 1200
rather than a waveform generator 930 (FIG. 9), as described above.
The waveform modulator 1200 inputs a plethysmograph signal from the
decoder 1120 rather than oxygen saturation and pulse rate
measurements, as described with respect to FIG. 9, above. Further,
the waveform modulator 1200 provides an modulated waveform 1132 to
the pulse oximeter monitor 360 rather than a synthesized waveform,
as described with respect to FIG. 9. The modulated waveform 1132 is
a plethysmographic waveform modulated according to the monitor
drive signal input 1134. That is, the waveform modulator 1200 does
not synthesize a waveform, but rather modifies the received
plethysmograph signal 1124 to cause the monitor 360 to calculate
oxygen saturation and pulse rate generally equivalent (within
clinical significance) to that derivable by a compatible,
calibrated pulse oximeter directly from the sensor signal 1012
(FIG. 10). The waveform modulator 1200 is described in further
detail with respect to FIG. 12, below.
[0050] FIG. 12 shows a waveform modulator 1200 having a demodulator
1210, a red digital-to-analog converter (DAC) 1220, an IR DAC 1230,
a red amplifier 1240, an IR amplifier 1250, a modulator 1260, a
modulator control 1270, a look-up table (LUT) 1280 and a ratio
calculator 1290. The waveform modulator 1200 demodulates red and IR
plethysmographs ("pleths") from the decoder output 1124 into a
separate red pleth 1222 and IR pleth 1232. The waveform modulator
1200 also adjusts the amplitudes of the pleths 1222, 1232 according
to stored calibration curves for the sensor 310 (FIG. 10) and the
monitor 360 (FIG. 11). Further, the waveform modulator 1200
re-modulates the adjusted red pleth 1242 and adjusted IR pleth
1252, generating a modulated waveform 1132 to the monitor 360 (FIG.
11).
[0051] As shown in FIG. 12, the demodulator 1210 performs the
demodulation function described above, generating digital red and
IR pleth signals 1212, 1214. The DACs 1220, 1230 convert the
digital pleth signals 1212, 1214 to corresponding analog pleth
signals 1222, 1232. The amplifiers 1240, 1250 have variable gain
control inputs 1262, 1264 and perform the amplitude adjustment
function described above, generating adjusted red and IR pleth
signals 1242, 1252. The modulator 1260 performs the re-modulation
function described above, combining the adjusted red and IR pleth
signals 1242, 1252 according to a control signal 1272. The
modulator control 1270 generates the control signal 1272
synchronously with the LED drive signal(s) 1134 from the monitor
360.
[0052] Also shown in FIG. 12, the ratio calculator 1290 derives a
red/IR ratio from the demodulator outputs 1212, 1214. The LUT 1280
stores empirical calibration data for the sensor 310 (FIG. 10). The
LUT 1280 also downloads monitor-specific calibration data from the
ROM 1160 (FIG. 11) via the ROM output 1158. From this calibration
data, the LUT 1280 determines a desired red/IR ratio for the
modulated waveform 1132 and generates red and IR gain outputs 1262,
1264 to the corresponding amplifiers 1240, 1250, accordingly. A
desired red/IR ratio is one that allows the monitor 360 (FIG. 11)
to derive oxygen saturation measurements from the modulated
waveform 1132 that are generally equivalent to that derivable
directly from the sensor signal 1012 (FIG. 10).
[0053] One of ordinary skill in the art will recognize that some of
the signal processing functions described with respect to FIGS.
8-11 may be performed either within a sensor module or within a
monitor module. Signal processing functions performed within a
sensor module may advantageously reduce the transmission bandwidth
to a monitor module at a cost of increased sensor module size and
power consumption. Likewise, signal processing functions performed
within a monitor module may reduce sensor module size and power
consumption at a cost of increase transmission bandwidth.
[0054] For example, a monitor module embodiment 900 (FIG. 9)
described above receives measured pulse oximeter parameters, such
as oxygen saturation and pulse rate, and generates a corresponding
synthesized waveform. In that embodiment, the oxygen saturation and
pulse rate computations are performed within a sensor module 800
(FIG. 8). Another monitor module embodiment 1100 (FIG. 11), also
described above, receives a plethysmograph waveform and generates a
remodulated waveform. In that embodiment, minimal signal processing
is performed within a sensor module 1000 (FIG. 10). In yet another
embodiment, not shown, a sensor module transmits a plethysmograph
waveform or a decimated plethysmograph waveform having a reduced
sample rate. A corresponding monitor module has a signal processor,
such as described with respect to FIG. 8, in addition to a waveform
generator, as described with respect to FIG. 9. The signal
processor computes pulse oximeter parameters and the waveform
generator generates a corresponding synthesized waveform, as
described above. In this embodiment, minimal signal processing is
performed within the sensor module, and the monitor module
functions are performed on the pulse oximeter parameters computed
within the monitor module.
Wireless Multiple Parameter Measurements
[0055] FIGS. 13-14 illustrate a multiple parameter communications
adapter. FIG. 13 illustrates a multiple parameter sensor module
1300 having sensor interfaces 1310, one or more signal processors
1330, a multiplexer and encoder 1340, a transmitter 1350, a
transmitting antenna 1370 and a controller 1390. One or more
physiological sensors 1301 provide input sensor signals 1312 to the
sensor module 1300. Depending on the particular sensors 1301, the
sensor module 1300 may provide one or more drive signals 1312 to
the sensors 1301 as determined by the controller 1390. The sensor
interfaces 1310 input the sensor signals 1312 and output one or
more conditioned signals 1314. The conditioned signals 1314 may be
coupled to the transmitter 1350 or further processed by the signal
processors 1330. If the sensor module configuration utilizes signal
processors 1330, it derives multiple parameter signals 1332
responsive to the sensor signals 1312, which are then coupled to
the transmitter 1350. Regardless, the transmitter 1350 inputs a
baseband signal 1342 that is responsive to the sensor signals 1312.
The transmitter 1350 modulates the baseband signal 1342 with a
carrier to generate a transmit signal 1354, which is coupled to the
transmit antenna 1370 and communicated to a corresponding receive
antenna 1470 (FIG. 14), as described with respect to FIG. 6, above.
Alternatively, there may be multiple baseband signals 1342, and the
transmitter 1350 may transmit on multiple frequency channels, where
each channel coveys data responsive to one or more of the sensor
signals 1314.
[0056] As shown in FIG. 13, the sensor interface 1310 conditions
and digitizes the sensor signals 1312 as described for a single
sensor with respect to FIG. 6, above. The resulting conditioned
signals 1314 are responsive to the sensor signals 1312. The signal
processors 1330 perform signal processing on the conditioned
signals 1314 to derive parameter signals 1332, as described for a
single conditioned signal with respect to FIG. 6, above. The
parameter signals 1332 may be physiological measurements such as
oxygen saturation, pulse rate, blood glucose, blood pressure, EKG,
respiration rate and body temperature to name a few, or may be
intermediate results from which the above-stated measurements may
be calculated or derived. The multiplexer and encoder 1340 combines
multiple digital word or serial bit streams into a single digital
word or bit stream. The multiplexer and encoder also encodes the
digital word or bit stream to generate the baseband signal 1342, as
described with respect to FIG. 6, above.
[0057] FIG. 14 illustrates a multiple parameter monitor module 1400
having a receive antenna 1470, a receiver 1410, a demultiplexer and
decoder 1420, one or more waveform processors 1430 and a monitor
interface 1450. The receiver 1410 inputs and demodulates the
receive signal 1412 corresponding to the transmit signal 1354 (FIG.
13) to generate a baseband signal 1414 as described with respect to
FIG. 7, above. The demultiplexer and decoder 1420 separates the
symbol streams corresponding to the multiple conditioned signals
1314 (FIG. 13) and/or parameter signals 1332 (FIG. 13) and
translates these symbol streams into multiple decoded signals 1422,
as described for a single symbol stream with respect to FIG. 7,
above. Alternatively, multiple frequency channels are received to
generate multiple baseband signals, each of which are decoded to
yield multiple decoded signals 1422. The waveform processors 1430
input the decoded signals 1422 and generate multiple constructed
signals 1432, as described for a single decoded signal with respect
to FIGS. 7-12, above. The monitor interface 1450 is configured to
communicate the constructed signals 1432 to the sensor ports of a
multiple parameter monitor 1401 or multiple single parameter
monitors, in a manner similar to that for a single constructed
signal, as described with respect to FIGS. 7-12, above. In
particular, the constructed signals 1432 are adapted to the monitor
1401 so that measurements derived by the monitor 1401 from the
constructed signals 1432 are generally equivalent to measurements
derivable directly from the sensor signals 1312 (FIG. 13).
[0058] A physiological measurement communications adapter is
described above with respect to wireless communications and, in
particular, radio frequency communications. A sensor module and
monitor module, however, may also communicate via wired
communications, such as telephone, Internet or fiberoptic cable to
name a few. Further, wireless communications can also utilize light
frequencies, such as IR or laser to name a few.
[0059] A physiological measurement communications adapter has been
disclosed in detail in connection with various embodiments. These
embodiments are disclosed by way of examples only. One of ordinary
skill in the art will appreciate many variations and modifications
of a physiological measurement communications adapter within the
scope of the claims that follow.
* * * * *